Apparatus for automatic regulation, during working, of the distance between the electrodes of electrolytic cells having a movable mercury cathode



p 4, 1962 c. DEPREZ EIAL ,05 13 APPARATUS FOR AUTOMATIC REGULATION,DURING WORKING. OF THE DISTANCE BETWEEN THE ELECTRODES 0F ELECTROLYTICCELLS HAVING A MOVABLE MERCURY CATHODE Filed Feb. 7, 1958 5 Sheets-Sheetl Sept. 4, 1962 c. DEPREZ ETAL 3,052,618

APPARATUS FOR AUTOMATIC REGULATION, DURING WORKING, OF THE DISTANCEBETWEEN THE ELECTRODES 0F ELECTROLYTIC CELLS HAVING A MOVABLE MERCURYCATHODE 5 Sheets-Sheet 2 Filed Feb. 7, 1958 CLLII'.

CLLI

ch I INVENTORS CHARLES DEPREZ,

RENE BULTE a BY RENE CRABB ATTORNEY? Sept; 4, 19 c. DEPREZ EI'AL3,052,618

APPARATUS FOR AUTOMATIC REGULATION, DURING WORKING, OF THE DISTANCEBETWEEN THE ELECTRODES 0F ELECTROLYTIC CELLS HAVING A MOVABLE MERCURYCATHODE Filed Feb. 7, 1958 5 Sheets-Sheet 3 CLLI 3,052,618 RKING, 0FECTROLYTIC ABLE MERCURY CATHODE S pt- 4, 1962 c. DEPREZ ETAI.

APPARATUS FOR AUTOMATIC REGULATION, DURING W0 THE DISTANCE BETWEEN THEELECTRODES OF EL CELLS HAVING A MOV 5 Sheets-Sheet 4 Filed Feb. 7, 1958Sept. 4, 1962 c. DEPREZ ETAL 3,052,618

APPARATUS FOR AUTOMATIC REGULATION, DURING WORKING, OF THE DISTANCEBETWEEN THE ELECTRODES OF ELECTROLYTIC CELLS HAVING A MOVABLE MERCURYCATHODE Filed Feb. 7, 1958 Sheets-Sheet 5 Motor 5 Motor- 34 T 3 I 1%: -&102,) 220 [lec/mma gn at .9 Motor /2 102/2) #50) 0 1) 5in r- L 213'lectramaynet 3 270(2) #56) flotarl 12 my 1% 1 il- United States Patent3,052,618 APPARATUS FOR AUTOMATIC REGULATION,

DURING WORKING, 0F TIE DISTANCE BE- TWEEN THE ELECTRODES OF ELECTROLYTICggIELS HAVING A MOVABLE MERCURY CATH- Charles Deprez, Uccle-Brussels,Ren Bult, Forest-Brussels, and Ren Crabbe, Boitsfort-Brusseis, Beigium,assignors to Solvay & Cie., Brussels, Belgium, a Belgian company FiledFeb. 7, 1958, Ser. No. 713,940 Claims priority, application Belgium Feb.9, 1 .957 12 Claims. (6!. 204-225) In cells for the electrolysis ofaqueous solutions having a moving mercury cathode of the horizontaltype, it is necessary to regulate periodically the distance between theelectrodes, in order to compensate for the wear of the graphite anodes.

Various devices have already been proposed enabling this regulation tobe effected without interrupting the operation of the cell. W. C.Gardiner, for example, describes in Chemical Engineering, volume 54 ofNovember 1947, pages 108 to 112, supporting rods for the lead-in of thecurrent to the anode plates which are ar ranged in the lid of theelectrolytic cell in such a manner that the rotation of the said rodscauses the anode plates to descend towards the moving cathode. The firstregulation is eiiected in the state of rest when the anodes are renewed,and during operation the wear of the anodes is periodically compensatedfor by the rotation of the supporting rods which causes the anodes todescend a distance controlled by the voltage, read from a voltmeter,existing between the anodes and the moving cathode.

It has also been proposed in Belgian Patent No. 451,- 762 to regulatethe distance between the anodes and the moving mercury cathode duringthe operation of the cell by displacing the plates supporting the anodesand serving as a lid for the electrolytic cell. For this purpose, thelateral sides of the cells are fitted with fixed supports with whichthreaded rods engage, these rods being fixed to the plates which arethus suspended from the fixed supports and maintained in position bynuts screwed on the threaded rods and tightened on the fixed supports.By loosening the nuts, the plates are caused to descend thus enablingthe wear of the anodes to be compensated for during operation.

In these two devices the regulation depends on the estimation of theoperator and is thus not safeguarded against errors. For this reasonthere have been proposed, for example in British Patent No. 627,349,devices comprising, on the bottom of the cell which constitutes thesupport for the moving mercury cathode, supports on which the freelysuspended graphite anodes rest. When and as the graphite disappears, theanodes descend towards the cathode and the distance between theelectrode is thus theoretically kept constant and determined by thedimensions of the supports. These devices have two disadvantages; on theone hand, the supports constitute a permanent obstacle to the uniformcirculation of the mercury and may constitute barriers opposing thecarrying away by the mercury of impurities or solid residues which mayform permanent local short-circuits detrimental to the good operating ofthe cell; on the other hand, the wear is less rapid at the point ofcontact between the supports and the anode than elsewhere and thedistance between the electrodes is diflicult to estimate. To obviatethese disadvantages, it has been proposed in Belgian Patent No. 522,772and US. Patent No. 2,784,157 to provide cavities in the support of themoving mercury cathode wherein retractable calipers may move whichemerge from the support surfiace to ice a predetermined height and onwhich the anodes may rest during the regulation.

Hitherto all devices for carrying out processes of regulation have beenoperated by hand.

The invention relates to a process for regulating during operation thedistance between the electrodes of electrolytic cells having a movingmercury cathode and to an automatic device enabling all of the anodes tobe regulated within a minimum of time thus obtaining a preciseregulation independent of any human factor of estimation.

We have found the surprising fact that it is possible without majordisadvantages to tolerate for a limited time a contact between an anodeand the moving mercury cathode of an electrolytic cell. The processaccordingly consists in successively gripping each anode by its supportrod and current lead which projects through the lid of the cell, causingit to approach the cathode, until the amperage attains a given value asa function of the voltage existing in the cell or undergoes a rapidincrease, particularly by the contact between the electrodes, and insubsequently displacing the anode in the opposite direction to adistance substantially corresponding to the optimum yield of theelectrolytic cell.

The device for automatically carrying out the process according to theinvention comprises a combination of two carriages the first of whichruns on a runway parallel to the longitudinal axis of the cell, thesecond running at right angles to the first. The second carriage isfitted with pincers having several catches arranged concentrically tothe support of the anode to be displaced which is movable in a verticaldirection, the movements of the carriage and of the pincers beingelectrically controlled according to a pre-established plan from acontrol station situated at any point of the electrolytic plant or atone end of the cell or .even on one of the two carriages.

FIG. 1 of the accompanying drawings illustrates a de vice for carryingout the process according to the invention;

FIG. 1a is a similar view of the device seen in FIG. 1 but showing onlythe lower half of FIG. 1 and illustrating the cells and anodes withwhich the device can be associated;

FIG. 2 shows a detail of the fastening system of the device to the lidof the electrolytic cell;

FIG. 3 diagrammatically illustrates the various connections existingbetween the various members ensuring the automatic operation of thedevice;

FIG. 4 diagrammatically illustrates the supply circuits of all theoperating members of the device;

FIG. 5 diagrammatically illustrates an electrolytic plant in plan view,the arrows indicating the direction in which the regulation is effected;and

FIG. 6 shows a modification of the contact plug in the form of acontactor.

It is to be understood that the invention is in no way limited to theexamples given in these figures.

The device according to the invention is fitted with a series of relaysand contactors ensuring its automatic operation. It is known that acontactor may simultaneously ensure the opening and the closing ofdifieren-t circuits thus permitting several simultaneous possibilities.In order to indicate these circuits and thus the various possibilities,there are used in FIGURES 3 and 4 of the accompanying drawings numberswhich are placed in brackets after the reference number of the contactorin question. Moreover, some contactors are open in the state of rest,while others are closed. In order to indicate this difference, thesymbols 0 and c are used to indicate open and closed, respectively.Thus, the contactor 111(1)c denotes that the contactor 111, circuit 1,is closed in the position of rest, that is to say open when it ismechanically actuated, whereas the contactor 111(2)o denotes thecontactor 111, circuit 2, is open in the position of rest, that is tosay closed when it is mechanically actuated. Thus, when the contactor111 is actuated, the circuit 1 is interrupted whereas the circuit disclosed. a

The device shown in FIG. 1 comprises in outline a large carriage Callowing the longitudinal displacement of the device, a small carriage Rmoving transversely and carrying the pincers, the system for fasteningthe pincers to the tubular piece P fixed on the lid of the electrolyticcell and the system for opening and closing the pincers on the rodsupporting the anode. Finally, the assembly of the device is fitted withvarious control and regula tion systems.

The large carriage is composed of a chassis C supported by two axles(not shown) on which two rollers (not shown) are arranged. One axle isdriven by the motor 1 fitted with a speed reducer. The starting of themotor 1 is controlled by means of the contactor 1010. The lateraltraverses of the chassis comprise fingers 2 actuated by electromagnets3; these fingers fix the cartriage in a predetermined position byengaging with stopping notches 4. The fingers 2 are raised by thefeeding of the electro-magnets 3 which is determined by means of thecontactors 102(2)0, 103(1)0, 104(1)0, 105(2)c, 106(3))0, 107(1)c,107(2)c, the relays 201 and 220(2), the latter being timed to one seconddelay, viz. ensuring contact for one second after removal of actuatingvoltage. One of the traverses carries shoes '50 and 51 whose purposewill be explained below. On the other hand, the motor 5 is fixed on oneof the traverses, fitted with a speed reducer and actuating the doublecontact plug 6 which engages with the double current supply 70 each ofwhose sockets is connected at a dilferent point with the current path,that is to say connected with a difierent point of the copper bar CUserving for the circulation of the current from the sole of theelectrolytic cell to the anodes of the immediately adjacent cell. Thiscontact plug verifies the amperage existing in the cell when the anodeAn contacts the cathode Hg, above which is formed the electrolyte Sa andbelow which is the sole So of the cell. The contact plug 6 is subject tocorrosion. A contactor is therefore preferably used as shown in FIG. 6.This contactor is completely enclosed in a sealed casing 400; instead ofthe contact plug 6, the axle controlled by the motor 5 is fitted with afinger 401 which engages the movable piece 402 of the contactor. Thismovable piece, when descending, ensures the closing of the circuits 403and 404 connected with different points of the copper bar 406 whichensures the circulation of the current from the sole S of theelectrolytic cell CLLII to the anodes An of the adjacent cell CLLI. Themovable piece 402 is fitted with a return spring 405. The motor isactuated by means of the contactors 106(4)0, 108(1)0, 108(2)0, 109(4)0,(timed to one second), 110(2)0, 110(3)o, 110(4)c, the relays 202, 203,204, 205 (timed to one second) and the push button 301(1)0 (timed to onesecond).

The small carriage R also comprises two axles E fitted with rollers G.One of these axles is driven by the motor 7 fitted with a speed reducerand actuated by means of the contactors- 106(2)0, 111(2)o, 116(1)o,116(2)c, 116(3)c and the relays 206 and 218. The device for fasteningthe small carriage to the large carriage comprises the finger 8 actuatedby the electromagnet 9 and permits the immobilization of the smallcarriage due to the stopping notches 10 provided on the transverse sidemembers A. Voltage is applied to and cut off from the electromagnet 9 bymeans of the contactors 102(2)0, 103(1)o, 105(1)c, 106(1)c, 106(5)0,111(1)c, 117e, the relays 207, 208, 220(1) (timed to one second), andthe push button 301(2)0. The small carriage is fitted with a chassis Ccomprising four elastic supports 11 to which the pincers and the varioussystems of regulation and control are fastened; the assembly supportedby the elastic supports 11 is thus rendered independent of the carriagesduring the control operations.

The pincers consist of several parts which may be operatedsimultaneously or separately by any automatic or non-automatic electricdevice. This entire assembly is enclosed in the casings C and 0.; whichare tight and resistant to corrosive liquids.

The system of fastening the device to the tubular piece P surroundingthe supporting rod of the anode and fastened to the lid of theelectrolytic cell comprises the motor 12; fitted with a speed reducerand a frictional coupling F The motor 12 is actuated by means of thecontactors 103(2)o, 103(3)0, 109(1)0 (timed to one second), 110(1)0,112(1)c, 112(2)c, 113(2)0, 113(3)c and the relays 209, 210(2) (timed toone second), 211 and 212. The motor 12 actuates by means of a pinion 13,having teeth inclined at 45, and a rack 14 having the form of a bracket,the fastening tube 15 fitted with bayonet notches 1'6 fastening it tothe projection 17 of the tubular piece P which is fastened on the lid ofthe electrolytic cell around the rod supporting the anode An. FIG. 2 isa fragmentary view of the rack 14: it is made of two branches arrangedat right angles. The pinion 13 to which a guide roller is fixed (notshown) engages in the first instance the rack arranged on the Verticalbranch which results in the descent of the fastening tube 15. At the endof its course, the pinion 13 engages the rack disposed on the horizontalbranch thus causing the securing tube to turn and fastening it, by meansof the bayonet notches 16, to the projection of the tubular piece P. Itshould be noted that the rod supporting the anode should be arranged inthe lid of the electrolytic cell in such a manner that the cell will beperfectly tight. To this effect, an adequate device will be used such ashas been described, for example, in Belgian Patent No. 457,712.

The pincers proper comprise the catches 18 joined to the integral axles19 of the support 2 0. The lower end of each catch is intended to engagethe groove 21 cut into the rod supporting the anode An. The upper partof each catch is fitted with a head 22 engaged by the female cone 23 andthe male cone 214. When the catches are open, the cones 23 and 24 arehooked to a projection 26 by means of a small hooked rod 25. The smallrod 25 is fitted with a spring (not shown) which tends to hold it fastto the support 20 and is movable around the axle 42. A notch is providedin the support 20 for passing the hook of the small rod 25 When thecatches are closed, the push button carried by the piece 43 which iscapable of sliding in the support 20' and fitted with a return spring44, is in contact with the rod supporting the anode. The piece 43carries a lever 25' arranged in a groove of the support 20 and fittedwith a spring 45 which tends to keep it against the wall of the'support20; this lever is displaced upwards as soon as the push button is put incontact with the rod supporting the anode and it engages the heel of thesmall rod 25 which is then freed from the projection 26. The cone 24engages the springs 29*, the relaxation of which causes the cones 23 and2.4 to descend thus causing the catches to be closed.

The operating mechanism of the pincers comprises the motor 34 controlledby means of the contactors 102(2) 0, 109(5)0 (timed to one second),110-(1)0, 115(1):), the relays 210(1) (timed to one second), 216, 217and 219. The motor 34 ensures the descent and the ascent of the pincersby means of trains of reduction gears 36 and 37, the friction coupling38 and the endless screw 35 at which the support 20 is suspended. Theverification of the rising distance of the pincers is effected by thesynchro circuit interrupter 4 1 having a controllable course which isset in motion by means of an endless screw 40 which engages the endlessscrew 35. The controllable interrupter synchro 41 completes one rotationof 360 for a vertical movement of the pincers of 100 millimetres. Asafety device reversing the rotation of the motor 34 is provided by thetwo generator dynamos 39 actuated by means of the gear trains 36 and 37and by the gear wheels D.

The restitution mechanism of the cones 2 3 and 24 comprises the motor 36fitted with a friction coupling F which actuates a tubular gear Wheel 31the lower end of which is threaded and fitted with a nut 32, with whichthe rods 33 engage, to raise the cones 23 and 2d. The motor 30 isactuated by means of the contactors 109(2) 0, 109(3)0 (both timed to onesecond), 114(1)0, 114(2)0, the relays 213, 214, 215' and thecontrollable interrupter synchro 41.

It should be mentioned that all the motors are fitted with a mechanicalbrake whose jaws are actuated by an electromagnet arranged in series orin parallel with the motor. Stopping of the supply to the motor givesrise to the stoppage of the supply to the electromagnet which determinesthe braking of the movement of the motor by locking its axle by the jawsof the brake. As a matter of course, the motors, contactors and relaysare protected from shock and covered by a jacket which is resistant tocorrosive fluids.

The various contactors are actuated by the following pieces:

Large carriage C 105 (1)c and (2)0; 1tl7(1)c and Small carriage R:106(1)c, (2) 0, (3 0, (4)0, (5) 0, 111(1)c and (2)0, 1170;

Finger 2: 113 1.10'(1)0, (2)0, (3)0 and (4)0;

finger 8: 113(1)0, (2)0'and (3)0; 116(1)0, (2)0 and Contact plug 6:Hid-(1)0, (2)0and (3)0; 108(1)0 and Fastening tube 103 1 2 0 and 3 0;112 1 and (2) 0;

The end 18 of the catches actuates a contactor (not shown) which has theeffect of diminishing the speed of rotation of the motor 34- whichrotates fairly slowly when the catches are closed over the rodsupporting the anode;

The not 32: the contactor, timed to one second, 109(1)0, (2)0, (3)0,(4)0 and (5)0 and the contactor 114(1)0 and (2)0;

All of the pincers: 102(1)0 and (2)0;

The contactor 115'(1)0 and (2)0 is actuated by mechanisms describedbelow.

FIG. 5 shows a diagrammatic plan view of an electrolytic plant.According to this diagram, the device has just effected the control ofthe cell CLL 1 and is in the position of end of contro indicated by PRthat is to say the small carriage R has started from a starting point PDand has consecutively stopped level with the anodes a a a a 032, and hasthen moved up to the point end of control FR The device is thendisplaced according to the dotted arrow PR by a rolling bridge and isnow situated in the axis of the first series of anodes b b b and 0 ofthe cell CLLII. The large carriage is connected to an alternativecurrent source of 110-115 volts and fastened by means of the fingers 2which engage with the notches 4 shown in FIG. 1. FIG. 3 summarises theposition of all of the contactors at this instant: the pincers are inthe upper position and actuate the contactor 1020 (both circuits beingclosed). The contactor 1150 is not actuated (both circuits being open).The large carriage being bolted, the fingers 2 are in the notches 4 andno longer actuate 1010 (open circuit), but actuate the contactor 110(circuits (1), (2) and (3) closed-circuit (4) open). In the lockedposition the large carriage cannot actuate the contactor 105 (bothcircuits closed); on the other hand, it actuates the contactor 1070(both circuits open). The nut 32 is in the low position on the threadedpart of the tubular gear wheel 31 and actuates the contactor 1140 (bothcircuits closed), whereas the contactor 10% is free (the five circuitsbeing open). The fastening tube 15 in the high position actuates thecontactor 1030 (the three circuits being closed). The

finger 8 which has fallen back actuates the contactors 113 (circuits (1)and (2) closed, circuit (3) open) and 116 (circuit (1) open, circuits(2) and (3) closed). The small carriage in the position PR actuates thecontactor 106 (circuit (1) open, circuits (2), (3), (4) and (5) closed),does not actuate 111 (circuit (1) closed and circuit (2) open) andactuates the contactor 117' (circuit open). The contact plug 6 being inthe high position, the contactor 11140 is actuated (the three circuitsbeing closed), while the contactor 1080 is in the position of rest (bothcircuits open).

The small carriage R being in FR the push button 301 of the control postis pressed thus starting the following series of operations:

(1) The small carriage moves towards the other end of the large carriageC while the contact plug 6 descends and plugs itself into the currentsupply 70. These operations analyze as follows:

(0) Motor 5: By the closing of 301(1), timed to one second, the motor 5is put under voltage and rotates in the direction corresponding to thedescent of the contact plug 6 thus causing the opening of the contactor11140; the circuits (2) and (3) of this contactor being open, voltage isapplied to the relay 204 thus enabling the motor 5 to be continuouslysupplied when 30 1(1) is re-opened. When the contact plug arrives at theend of the course, it actuates the contactor 11180 which closes; theclosing of the circuit (1) of this contactor leads to the end of thesupply of the motor 5, since the relay 2% is disconnected, whereas theclosing of the circuit (2) causes the application of voltage to therelays 202 and 2413, the latter preparing the re-ascending movement ofthe contact plug 6 by reversing the direction of rotation of the motor5.

(b) Electromagnet 9 and motor 7: The closing of the push-button 3tl1(2)timed to one second, determines the application of voltage to theelectromagnet 9 and the relays 2117 and 268; the finger 8 is lifted andactuates the contactor 116 whose circuit (1) closes, while the circuits(2) and (3) open: the motor 7 is placed under tension, the smallcarriage R moves and thereby no longer actuates the contactor 117a whichcloses; the electromagnet 9 remains under voltage when 301(2) isre-opened on account of the fact that 207 remains under voltage. Due toits displacement, the small carriage no longer actuates the contactor1116 (circuit (1) closed, circuits (2), (3), (4) and (5) open). After acertain course of the small carriage, the shoe 50 fixed at the end ofthe transverse side member A raises the contactor 111 (circuit (1) openand circuit (2) closed). In parallel with the contactor 111 thecontactor 117 is actuated and opens. The electromagnet 9 is thus nolonger fed, the finger 8 falls back and ceases to actuate 116: thecircuit (11) is thus open, the motor 7 is no longer fed, whereas thecircuits (2) and (3) of the contactor 116 are closed (applying thevoltage to the relays 206 and 218), the latter preparing the reversal ofthe direction of rotation of the motor 7. The small carriage continuesits course and the finger 8 is blocked in the notch 19 whereby thecontactor 113 (circuits (1) and (2) closed and circuit (3) open) isactuated.

(2) The action on the contactor 113 gives rise to the application ofvoltage to the motors 12 and 34 which respectively ensure the fasteningof the device to the cell and the descent of the pincers.

(0) Motor 12: Before the finger 8 actuates the contactor 113, thecircuit (3) of the contactor is closed and the relay 210 is undertension. This relay is timed to one second, the action on the contactor113 (closing of the circuits (2) and (3)) causes the application ofvoltage to the motor 12. The fastening tube 15 descends and frees thecontactor 1630 (the three circuits being open). Due to the opening ofthe circuit (1) of this contactor, no voltage can be applied to theelectromagnets 3 and 9, whereas the opening of the circuits (2) and (3)determines the application of voltage to the relay 211 thus enabling themotor 12 to be continuously fed when the relay 210(2) is re-opened. Itshould be kept in mind at this point that the pincers and the casings Cand C are independent of the small carriage R on account of the elasticsupports 11 thus permitting freeing movements of the pincers and thecasings. Due to the rack 14 having the shape of a cross-piece, theprojections of the tubular pincers P engage with the bayonet notches 16when the tube 15 descends, then by rotation of the tube 15 (horizontalbranch Y of the rack 14-) the whole is fastened to the tubular piece P.At this instant the tube 15 actuates the contactor 1120. The closing ofthe circuit (1) of this contactor interrupts the supply of the relay 211and thus that of the motor 12; the closing of the circuit (2) of thesame contactor causes the application of voltage to the relays 209 and212, the latter preparing the reascent of the tube 15 by reversing thedirection of rotation of the motor 12.

(b) Motor 34: 210(1) being timed to one second, the closing of thecontactor 1 13 (circuit (1)) determines the application of voltage tothe motor 34 and to the relay 220. The pincers start their rapiddescent, the rotation of the screw 35 causing the support 20 to descend,and thus the contactor 1020 is freed which results in the application ofvoltage to the relay 217 thus ensuring the continuous supply of themotor 34 when the relay 210(1) is re-opened. Since the pincers continueto descend, the push button 27 comes in contact with the rod supportingthe anode; the piece 43 has from now on an ascending movement withregard to the support 20 thus displacing the lever 28 upwards. The lever28, by leaning on the hook of the small rod 25, lifts it and frees itfrom the projection 26. The cones 23 and 24- are then immediately drivenout by the relaxation of the springs 29; the cone 24 separates the heads22 and the catches 18 close over the groove 21 cut in the supporting rodof the anode. The descending movement of the cones 23 and 24 and theclosing movement of the catches causes the closing of a contactor (notshown) and this has the effect of reducing the rotation speed of themotor 34 from 3000 rpm. to 1000 r.p.m., the anode thus slowly descendingtowards the moving cathode. On account of the drawback spring of thesmall rod 25 and of the lever 28, the heel of the small rod now strikesthe lateral part of the lever 28.

(3) The anode to be controlled approaches the moving mercury cathode andthe re-ascending movement of the pincers, in order to carry out theprocess according to the invention, is efiected by reversing thedirection of rotation of the motor 34. The reversal of the direction ofrotation of the motor 34 is carried out by closing the contactor 1150which is actuated indifiterently by one of the three followingmechanisms If the amperage verified by the contact plug 6 reaches agiven value as a function of the voltage existing in the cell;

If this amperage undergoes a rapid increase;

If the friction coupling 38 slips. The latter system is a safety device.If for any reason the two preceding mechanisms have not worked, thepincers continue to descend and the anode rests on the sole of the cellwhich represents a certain mechanical effort. The friction coupling 38is set in such a manner as to slide, beyond a certain tolerated effort.Below this tolerated effort it does not slide and the two generatingdynamos 39 which rotate at the same speed as the motor 34 supply thesame amount of current, and the difierence of potential between the twogenerators arranged opposite one another is nil. Beyond the toleratedeffort, the coupling slides and the two generators no longer rotate atthe same speed; there is thus a difierence of potential taken up by arelay (not shown) which actuates the contactor 1150. The closing of thiscontactor by any of the three mechanisms leads to the application ofvoltage to the relays 21 6 and 219,

8 the latter causing the reversal of the direction of rota-. tion of themotor 34 and thus the re-ascent of the pincers.

(4) The reversal of the direction of rotation of the motor 34 causes theopening of the contactor 1150, but since the relays 216 and 219 remainunder voltage, the direction of rotation of the motor 34 correspondingto the ascent of the pincers is maintained. Similarly, the relays 217still under voltage permit the continuous supply of the motor 34. Thereversal of the direction of rotation of the motor 3 determines moreoverthe extent of the displacement of the re-aseent of the pincers and thusof the anode, by the controllable interruptor 41 which operates by meansof the endless screw 40 only during the ascending movement of thepincers. After a controllable distance of ascent comprised between 0 and30 millimetres, the controllable interrupter synchro 41 closes, therelay 217 is no longer supplied and, thus, the motor 34 is no longersupplied and stops.

(5) The stopping of the motor 34 (closing 41(1)) causes the applicationof voltage to the motor 30 which actuates the tubular gear wheel 31. Thenut 32 arranged in the low position on the threaded part of the tubulargear wheel, ascends and lifts the cones 23 and 24 by means of the rods33 whose heads are fitted with an enlargement having the purpose ofrigidly fixing them to the nut 32 from a predetermined position; thesmall rod 25 hooks to the projection 26 and the catches 18 of thepincers spread open: this has the effect of freeing the contactor whichdetermines the slow speed of the motor 34. As the nut 32 rises to thehigh position on the threaded part of the tubular gear wheel, it freesthe contactor 114 which results in the application of voltage to therelay 213 thus permitting a continuous supply to the motor 30. The nut32, now arriving at the high position, actuates the contact 1090 timedto one second, that is to say the five circuits close during one second.The closing of the contactor 1090 has the effect:

(0) Of rearming the mechanism for the closing of the catches 18.Actually, the circuit (3) being closed, the relays 214 and 215, thelatter of which causes the reversal of the direction of rotation of themotor 30, are under voltage. The controllable interruptor synchro 41 isre-opened and the nut 32 re-descends to the low position on the tubulargear wheel thus compressing the springs 29 between the cone 24' and thenut 32. At the same time, the contactor 1090 is freed, the motor 30still being supplied because the relays 213 are under voltage, and itrotates in the direction corresponding to the descent of the nut 32, therelays 214 and 215 being under voltage. Having arrived at the lowposition, the nut 32 actuates the contactor 1140 thus closing thecircuits (1) and (2): the relays 213, 214- and 215 are no longer undervoltage, the supply of the motor 30 is interrupted and, at the same timethe direction of rotation is reversed, since 215 is no longer undervoltage.

(b) The closing of 109(1) causes the application of voltage to the motor12: the fastening tube 15 rotates, is freed from the projections 17 andthe tubular piece P and re-ascends: as a result, the contactor 1120 isfreed, the continuous supply of the motor 12 being ensured on account ofthe fact that voltage is applied to the relay 211, since 109(1) isre-opened within a second. Having arrived at the high position, the tube15 actuates the contactor 1030, the three circuits are closed causingthe supply of the relay 211 to be terminated and thus the stopping ofthe motor 12 and at the same time the reversal of the direction of itsrotation with a view to subsequent operation, the relays 209 and 212being no longer under voltage.

(0) The closing of 109(5) causes the application of voltage to the motor34: the pincers re-ascend, the controllable interrupter synchro 41 isopened. Having arrived at the high position, the pincers actuate thecontactor 1020, thus excluding the relays 216, 217' and 219 from thecircuit: the motor 34 is no longer supplied and 9 p the reversal of thedirection of rotation is prepared (219 out of circuit).

(6) Thus, there is again achieved the initial situation 1-b. It shouldbe mentioned here that when the motor 34 is under voltage, the relay 220is under voltage. Now, this relay is timed to one second and when thethe closing of the contactor 102 causes the stopping of the motor 34.,220 remains closed for another second and this determines theapplication of voltage to the electromagnet 9, the finger 8 which islifted acts on the contactor 116 whose circuit (1)0 closes, the motor 7is placed under voltage and the small carriage moves towards thefollowing anode and no longer acts on the contactors 111 (circuit (1)closed, circuit (2) open) and 117 (closed) thus permitting the supply ofthe electromagnet 9 when the relay 220(1) opens. After a certain courseof the small carriage, a shoe 51 situated on one of the side memberlifts 1170 which opens at the same time as 111(1); the electromagnet 9is no longer supplied, the finger 8 falls back and no longer actuates116, the circuit (1) of this contactor opens, the motor 7 is interruptedwhile the direction of rotation remains the same because the relays 206and 218 are still under voltage. The small carriage continues on itscourse, until the finger 8 engages with one of the stopping notches 10thus actuating the contactor 113 which controls the motors 12 and 34,and the operation starts again as under (2).

(7) After the control of the last anode of the series (for example 12the small carriage actuates the contactor 106 (circuit (1) open,circuits (2), (3), (4) and (5) closed); the nut 32 being in the highposition (raised by the cones 23 and 24), 1090 is closed. Simultaneouslywith the re-ascent of the pincers after the control of the last anode ofthe series and with the re-ascent of the fastening tube, the closing ofthe circuit (4) of the contactor 106 and of the circuit (4) of thecontactor 109 (timed to one second), places the motor 5 under voltage:the contact plug 6 re-ascends, freeing the contactor 1080, the relays202 and 203 which are under voltage enable the motor 5 to rotate in thedirection corresponding to the ascent of the contact plug 6; the relay204 is placed under voltage and thus allows the continuous supply of themotor 5 once the contactor 109(4) is re-opened. Having arrived at thehigh position, the contact plug 6 actuates the contactor 1040: thecircuits (2) and (3) being closed, the relays 202, 203 and 204 are nolonger supplied and the motor 5 stops while the reversal of thedirection of rotation is prepared (203 out of circuit).

(8) As soon as the contact plug 6 has re-ascended, the ire-ascendingmovement of the pincers, which is the longest movement, is terminated,and the pincers in the high position actuate the contactor 1020. Therelay 220 which remains closed for one second after the termination ofthe supply of the motor 34, applies voltage to the electromagnets 3 and9 and, as a result, the motors 1 and 7 are fed. The small carriage Rreturns to its starting position while the large carriage moves towardsthe following series of anodes (b [2 where it stops, locks itself andthe contact plug 6 descends to the current supply 70. These operationsanalyze as follows:

(a) Electromagnet 3: the relay 220(2) being closed, the closing of thecontactor 102(2) permits the supply of the electromagnet 3, since thecontactor 106 is still actuated by the small carriage R (see (7)). Atthe same time the relay 201 is placed under voltage thus ensuring thecontinuous supply of the electromagnet 9 when the relay 220(2) is openedand the contactor 106 is no longer actuated by the small carriage Rwhich moves simultaneously with the large carriage. The finger 2 islifted and actuates the contactor 1010, thus applying voltage to themotor 1: the large carriage moves and the contactor 107 thus no longerbeing actuated, is reclosed and ensures the continuous supply to theelectromagnet 9 when 220(2) is re-opened. Having arrived in the vicinityof the following series of anodes, the finger 2 approaches the stoppingnotch 4 having the shape of a shoe. This part of the notch is such asmomentarily to actuate the contactor 10 7c. It is re-opened and thusinterrupts the supply of the electromagnet 3. The finger 2 falls backand ceases to actuate 1010, the motor stops. As soon as the finger 2 hasengaged with the notch 4, the large carriage is locked. The contactor isactuated (circuits (1), (2) and (3) closedcircuit (4) open) as soon asthe finger 2 engages with the notch 4.

(b) Electromagnet 9 and motor 7. The relay 220(1) being closed, theclosing of the contactor 1020 causes the application of voltage to theelectromagnet'9 and the relays 207 and 208. The finger 8 being lifted,the contactor 116 is actuated, the closing of the circuit (1) givingrise to the application of voltage to the motor 7. As the small carriagemoves, the contactor 106 is no longer actuated, nor are the contactors111, circuit (1) closed, circuit (2) (open) and 117 (closed). After acertain course the smail carriage stops, the contactor 117 and 111 beingsimultaneously actuated by the shoe 50: the electromagnet is no longerunder voltage, the finger 8 falls back and ceases to actuate thecontactor 116 (circuit (1) open, circuits (2) and (3) closed): the motor7 stops and the reversal of the direction of its rotation is prepared bythe application of voltage to the relays 206 and 218.

(c) Motor 5: As soon as the contactor 110 is actuated by the finger 2,the motor 5 is placed under voltage (the relay 205 being timed to onesecond) and the contact plug 6 descends into the connector 70. Theoperation then continues as under (1(a) (9) The operations then continueas under (2) etc.

(10) Having arrived in front of the last series of anodes, the largecarriage C actuates the contactor 1056 which opens. The opening of thecontactor causes the complete stopping of the apparatus, when, afterhaving controlled the last anode, the small carriage R moves to theposition end of control FR Various safety devices are thus provided: themotor 1 (large carriage) cannot be set in motion (by means of theelectromagnet 3) if the contact plug 6 and the fastening tube 15 are notraised. The motor 7 (small carriage) can operate only if the tube 15 isin the high position. On the other hand, the motor 5 can be suppliedonly if the fingers 2 are engaged with the notches 4 ensuring thelocking of the large carriage. The motors 34, 12 and 30 can lbe suppliedonly if the large carriage is locked (fingers 2 in the notches 4-) andalso the small carriage (finger 8 in notch 10). It has been seen thatthe motors 1 and 7 ensuring the displacement of the large carriage andthe small carriage respectively can be put under voltage only if thefingers 2 and 8 are lifted. In order to provide this safety device, itis possible to use for example a magnetic coupling for connecting therollers to the axles, the electromagnet being placed under voltage whenthe fingers 2 and 8 are lifted.

Other safety devices are also provided: they have the efiect of insuringthat the re-ascent of the anode cannot be interrupted unless the currenthas regained a normal value. On the other hand, if the currentcirculating through the copper bars already exceeds the control valuewhich is made evident by a visible signal and an audible signal, theapparatus raises the anodes until the current falls to a normal value.At this instant, the apparatus stops and can be started again only by amanual operation which stops the visible and audible signals.

The device is not limited to the control operations described above. Itmay also, by using suitable contactors and appropriate relays, effectfor example the following operations- Lift and lower all anodes asimilar amount without previously placing the electrodes in contact;

Control the anode a then lower the following anodes 11 a a a 11 the sameamount as a ycontrol in, then b b b 12 and so forth.

In the case of control operations such as descri above, the dew'cepermits one to estimate the wear f the graphite anodes: it is suflicientto arrange a secure mark on the pincers, which passes before a scaleduring the vertical movement of the pincers, the distances of descent ofthe pincers during the consecutive controls giving the extent of thewear of the anodes.

It must be clearly understood that the device described above whichcomprises an assembly of mechanical pieces and systems of control,regulation and safety, is capable of numerous modifications which do notdepart from the scope of the invention, the examples given are in no waylimiting the range of the invention.

We claim:

1. Apparatus for the automatic controlled regulation of the distancebetween the graphite anodes and the mobile mercury cathode of anelectrolytic cell for the electrolysis of aqueous solutions, said anodeshaving supporting rods and said cell having a sole supporting saidmercury cathode with said sole being connected in series with the anodesof an adjacent cell by a copper bar to provide fiow of current betweenthe sole of said cell and the anodes of the adjacent cell, saidapparatus comprising first rails disposed on each side of said cell inparallel relationship with the longitudinal axis of the cell, a firstcarriage adapted to move along said rails above said supporting rods andcomprising a chassis made of crosspieces defining second rails, and asecond carriage received by said second rails, said second carriagebeing provided with pincers having a plurality of catches, said pincersbeing movable in the vertical direction and being adapted to seize saidrods supporting the anodes, the movements of the first and secondcarriages and of the pincers being controlled by motors provided withbrakes and actuated from a control post by means of con-taotors andrelays according to a predetermined program, the indication essentialfor the regulation being obtained by means of a contact plug connectedto two different points of said copper bar, said plug permittingmeasurement of the intensity of the current passing through the anodewhen the latter is placed in contact with the moving cathode.

2. Apparatus as defined in claim 1, wherein said first carriage isprovided with locking fingers and each first rail is provided withnotches to receive said locking fingers of the first carriage.

3. Apparatus as defined in claim 2, wherein said second carriage isprovided with looking fingers, said bar is provided with a connector inwhich is received said contact plug, and said firstcarriage comprises achassis made of two cross-pieces supported on axles which carry rollers,the axles being controlled by a motor, said cross-pieces having notchesto receive said locking fingers of said second carriage, and areversible motor for controlling the descent and reascent of saidcontact plug respectively into and out of said connector on the copperbar to ensure the circulation of the current between the sole of saidcell and the anodes of said adjacent cell.

4. Apparatus as defined in claim 3, wherein said rollers are connectedto said axles by means of a magnetic clutch, said rollers beingconnected when the fastening fingers of the first carriage are lifted.

5. :Apparatus as defined in claim 1, wherein said second carriagecomprises a chassis supporting said pincers for seizing the supportingrods of the anodes and said chassis further supporting means forcontrolling the gripping and releasing movement of said pincers, theassembly of pincers and of said control means being contained incasings.

6. Apparatus as defined in claim 5, wherein said chassis of said secondcarriage is fitted with two second axles carrying second rollers, saidsecond axles being controlled by a second reversible motor, and saidchassis carrying said locking fingers of the second carriage.

7. Apparatus as defined in claim 6, wherein said second rollers areconnected to said second axles by means of an electromagnetic clutch,said second rollers being connected when the locking fingers of saidsecond carriage are lifted.

8. Apparatus as defined in claim 5, wherein the motor which actuatessaid pincers is a reversible motor, and wherein said pincers comprise anendless screw on which a support is suspended, catches being pivoted onsaid support and a roller disposed on the upper part of each of saidcatches, said roller being engaged by two conical cams actuated bysprings.

9. Apparatus as defined in claim 8, wherein the screw of the pincers ismechanically connected with two generating dynamos by means of two geartrains and a friction coupling set for a tolerated mechanical efiort,whereby when said tolerated efiort is exceeded the coupling slides andthe reascent of the anode is brought about by the difference ofpotential developed by said two dynamos.

10. Apparatus as defined in claim 8, wherein said screw of the pincersis mechanically connected by means of an endless screw to the axle of aninterruptor of variable course which verifies the distance of thereascent of the anode to be controlled.

11. Apparatus as defined in claim 5, wherein each anode rod issurrounded by a tubular member provided with projections and whereinsaid chassis of the second carriage is fitted with a fastening tubeactuated by means of a rack having the shape of a cross-piece, saidfastening tube being provided with bayonet notches adapted to engagesaid projections in the tubular member.

12. Apparatus as defined in claim 5, wherein a system for opening andre-arming the catches is attached to said pincers, said systemcomprising a hollow tubular gear wheel having a threaded lower part, anut arranged on said threaded part, and rods which engage with the nutand are connected with a conical cam, and a reversible motor to actuatesaid tubular gear wheel.

References Cited in the file of this patent UNITED STATES PATENTS1,396,919 Brace Nov. 15, 1921 2,098,813 Rosseau -i Nov. 9, 19372,203,062 Schueler June 4, 1940 2,316,685 Gardiner Apr. 13, 19432,347,608 Owen Apr. 25, 1944 2,421,209 Lindner et a1. r May 27, 19472,542,523 Hirsh 1 Feb. 20, 1951 2,784,157 Deprez. Mar. 5, 1957 2,786,023Deprez Mar. 19, 1957 2,816,861 Castex Dec. 17, 1957 2,819,802 Hart Jan.14, 1958 FOREIGN PATENTS 470,517 Germany Dec. 27, 1928 1,070,329 FranceJuly 22, 1954

1. APPARATUS FOR THE AUTOMATIC CONTROLLED REGULATION OF THE DISTANCEBETWEEN THE GRAPHITE ANODES AND THE MOBILE MERCURY CATHODE OF ANELECTROLYTIC CELL FOR THE ELECTROLYSIS OF AQUEOUS SOLUTIONS, SAID ANODESHAVING SUPPORTING RODS AND SAID CELL HAVING A SOLE SUPPORTING SAIDMERCURY CATHODE WITH SAID SOLE BEING CONNECTED IN SERIES WITH THE ANODESOF AN ADJACENT CELL BY A COPPER BAR TO PROVIDE FLOW OF CURRENT BETWEENTH E SOLE OF SAID CELL AND THE ANODES OF AN ADJACENT CELL, SAIDAPPARATUS COMPRISING FIRST RAILS DISPOSED ON EACH SIDE OF SAID CELL INPARALLEL RELATIONSHIP WITH THE LONGITUDINAL AXIS OF THE CELL, A FIRSTCARRIAGE ADAPTED TO MOVE ALONG SAID RAILS ABOVE SAID SUPPORTING RODS ANDCOMPRISING A CHASSIS MADE OF CROSSPIECES DEFINING SECOND RAILS, ANDSECOND CARRIAGE RECEIVED BY SAID SECON RAILS, SAID SECOND CARRIAGE BEINGPROVIDED WITH PINCERS HAVING A PLURALITY OF CATCHES, SAID PINCERS BEINGMOVABLE IN THE VERTICAL DIRECTION AND BEING ADAPTED TO SEIZE SAID RODSSUPPORTING THE ANODES, THE MOVEMENTS OF THE FIRST AND SECOND CARRIAGESAND OF THE PINCERS BEING CONTROLLED BY MOTORS PROVIDED WITH BRAKES ANDACTUATED FROM A CONTROL POST BY MEANS OF CONTACTORS AND RELAYS ACCORDINGTO A PREDETERMINED PROGRAM, THE INDICATION ESSENTIAL FOR THE REGULATIONBEING OBTAINED BY MEANS OF A CONTACT PLUG CONNECTED TO TWO DIFFERENTPOINTS OF SAID COPPER BAR, SAID PLUG PERMITTING MEASUREMENT OF THEINTENSITY OF THE CURRENT PASSING THROUGH THE ANODE WHEN THE LATTER ISPLACED IN CONTACT WITH THE MOVING CATHODE.